Method of using low-strength proppant in high closure stress fractures

Abstract

A method comprising: introducing into a fracture within a subterranean formation a first treatment fluid comprising uncoated first proppant particulates; introducing into the fracture a second treatment fluid comprising non-hardenable coated second proppant particulates to form a proppant pack; and introducing into the fracture a third treatment fluid comprising hardenable coated third proppant particulates intermittently between a spacer fluid to form pillars.

What is claimed is: 
     
       1. A method of treating a subterranean formation having a fracture closure pressure exceeding about 8,000 psi, the method comprising the steps of:
 introducing a first treatment fluid comprising a plurality of uncoated first proppant particulates into at least one fracture within the subterranean formation and depositing at least a portion of the uncoated first proppant particulates in the fracture, wherein the uncoated first proppant particulates have a crush strength able to withstand pressures up to about 8,000 psi; 
 after introducing the first treatment fluid, introducing into the fracture a second treatment fluid comprising a plurality of non-hardenable coated second proppant particulates and depositing at least a portion of the non-hardenable coated second proppant particulates in the fracture, wherein the non-hardenable coated second proppant particulates comprise second proppant particulates coated with a tackifying agent, and the second proppant particulates have a crush strength able to withstand pressures up to about 8,000 psi; and 
 after introducing the second treatment fluid, introducing into the fracture a third treatment fluid comprising a plurality of hardenable coated third proppant particulates, wherein the hardenable coated third proppant particulates comprise third proppant particulates coated with a hardenable resin, and the third proppant particulates have a crush strength able to withstand pressures up to about 8,000 psi and wherein said third treatment fluid is introduced so that said hardenable resin composition on the third proppant particulates hardens when in the fracture so that the hardenable coated third proppant particles consolidate into one or more pillars able to withstand closure pressures above 8,000 psi. 
 
     
     
       2. The method of  claim 1 , wherein the uncoated first proppant particulates are no larger than 80 mesh, and the second proppant particulates and the third proppant particulates are no smaller than 60 mesh. 
     
     
       3. The method of  claim 1 , wherein the first proppant particulates are silica sand having a mesh size of about 80 to about 120. 
     
     
       4. The method of  claim 1 , wherein the first treatment fluid further comprises fibers. 
     
     
       5. The method of  claim 1 , wherein the second proppant particulates form a proppant pack in the fracture to retard movement of at least a portion of fines by adhering the fines to the non-hardenable coated second proppant particulates. 
     
     
       6. The method of  claim 5 , wherein the non-hardenable coating on the second proppant particulates comprises a tackifying agent selected from a group consisting of polyamides, polyesters, polyethers, polycarbamates and polycarbonates. 
     
     
       7. The method of  claim 5 , wherein the second treatment fluid further comprises fibers. 
     
     
       8. The method of  claim 5 , wherein the one or more pillars prevent third proppant particle flow-back in the fracture. 
     
     
       9. The method of  claim 8 , wherein the second proppant particulates and the third proppant particulates are silica sand having a mesh size from about 20 to about 50. 
     
     
       10. The method of  claim 8 , wherein the third treatment fluid further comprises fibers. 
     
     
       11. The method of  claim 8 , further comprising, after introducing the third treatment fluid, introducing a fourth treatment fluid comprising a plurality of hardenable coated fourth proppant particulates, wherein the hardenable coated fourth proppant particulates comprise fourth proppant particulates coated with a hardenable resin, and the fourth proppant particulates have a crush strength able to withstand pressures above 8,000 psi, and the hardenable coated fourth proppant particulates harden and consolidate into one or more pillars which prevents fourth proppant particle flow-back in the fracture. 
     
     
       12. The method of  claim 11 , wherein the fourth treatment fluid further comprises fibers. 
     
     
       13. The method of  claim 11 , wherein the uncoated first proppant particulates are no larger than 80 mesh, and the second proppant particulates and the third proppant particulates are no smaller than 60 mesh. 
     
     
       14. The method of  claim 13 , wherein the fourth proppant particulates are synthetic proppant particulates. 
     
     
       15. The method of  claim 14 , wherein the first treatment fluid, the second treatment fluid, the third treatment fluid and the fourth treatment fluid are introduced into the subterranean formation for use in a fracturing operation using one or more pumps. 
     
     
       16. The method of  claim 1 , wherein the hardenable coating on the third proppant particulates comprises the hardenable resin and a hardening agent. 
     
     
       17. The method of  claim 16 , wherein the hardenable resin is selected from a group consisting of bisphenol A-epichlorohydrin resin, polyepoxide resin, novolak resin, polyester resin, phenol-aldehyde resin, urea-aldehyde resin, furan resin, urethane resin and mixtures thereof, and wherein the hardening agent is selected from a group consisting of 4,4′-diaminodiphenyl sulfone, amines, amides, hexachloroacetone, 1,1,3-trichlorotrifluoroacetone, benzotrichloride, benzylchloride and benzalchloride. 
     
     
       18. The method of  claim 11 , wherein the hardenable coating on the fourth proppant particulates comprises the hardenable resin and a hardening agent. 
     
     
       19. The method of  claim 18 , wherein the hardenable resin is selected from a group consisting of bisphenol A-epichlorohydrin resin, polyepoxide resin, novolak resin, polyester resin, phenol-aldehyde resin, urea-aldehyde resin, furan resin, urethane resin and mixtures thereof, and wherein the hardening agent is selected from a group consisting of 4,4′-diaminodiphenyl sulfone, amines, amides, hexachloroacetone, 1,1,3-trichlorotrifluoroacetone, benzotrichloride, benzylchloride and benzalchloride.